This invention relates to a method of producing vanadium and alloys thereof. More particularly, it relates to such a method one step of which includes the reducing of vanadium oxides in a plasma arc torch.
In the past, vanadium and alloys thereof, e.g. ferrovanadium, have been produced in an electric arc furnace by reducing vanadium oxides in the high temperature zone between two or more graphite electrodes submerged in a bath containing vanadium oxides and a reductant such as carbon. Fluxes and steel scrap or iron were also present in the bath, if desired.
Vanadium was also produced by heating vanadium oxides under vacuum and in the presence of carbon in an electric resistance furnace. This process was carried out in batches and a relatively long times, e.g. several hours.
As described in U.S. Pat. No. 2,709,739 to J. C. R. Kelley, Jr. vanadium metal powder was also produced by first reducing vanadium pentoxide to vanadium trioxide. In order to avoid a hard end product having poor ductility, it was essential to reduce the pentoxide in a moist atmosphere at relatively low temperatures, e.g. 450.degree. to 650.degree. C. (840.degree. to 1200.degree. F.). The resultant trioxide was subsequently reduced to the pure metal by reacting the trioxide with calcium in a metal bomb.
In an effort to produce vanadium and alloys thereof in a more rapid and substantially continuous process, attempts have been made to reduce vanadium pentoxide in a plasma arc torch. However, such attempts have at times proved unsuccessful, as the inlet ports of the torch inevitably became clogged, thereby blocking entry of additional vanadium pentoxide.
U.S. Pat. No. 3,765,870 to Maurice G. Fey et al. discloses that vanadium may be produced by reducing vanadium oxides in a plasma arc torch with hydrocarbon radicals. Fey et al. do not disclose which vanadium oxides may be reduced by these radicals. They do disclose that carbon ions and atoms are not effective in reducing such oxides.
It is an object of this invention to provide a process for producing vanadium and alloys thereof in which vanadium oxides are reduced rapidly and with a very high yield.